Importance

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Abstract

A voltage overstress protection device consists of a four-layer diode having a buried region of higher impurity concentration adjacent the central junction of the device. The buried region is divided into a plurality of small regions to ensure an even distribution of energy dissipation across the structure. The cathode of the device may be perforated by shorting dots of the material of the second layer to determine the holding current of the device, and where this is done the small buried regions are aligned with parts of the cathode and not with the shorting dots. Two devices may be formed in opposite senses in the same body of semiconductor material and connected together in antiparallel to provide protection against voltage surges of either polarity. Two antiparallel pairs of devices may be formed in a single semiconductor body to provide protection against separate voltage surges on two lines and also against different voltage surges between the two lines.

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First Claim